Decreasing Incidence of the Multisystem Inflammatory Syndrome in Children Over 3 Pandemic Waves.

In this nationwide retrospective study, a substantial decline in the incidence of multisystem inflammatory syndrome in children over 3 successive pandemic waves characterized by different severe acute respiratory syndrome coronavirus 2 variants was documented-from 3.4 of 1000 to 1.1 of 1000 and finally to 0.25 of 1000 confirmed severe acute respiratory syndrome coronavirus 2 positive cases (P < 0.0001), respectively, whereas clinical findings and severity did not significantly vary.

Seroprevalence of anti-SARS-CoV-2 antibodies among children and their parents in Greece.

School closures were enforced as measures to restrain the COVID-19 pandemic, based on the assumption that young children may play a key role in SARS-CoV-2 spread. This study aims to determine the prevalence of SARS-CoV-2 IgG antibodies in children and corresponding parents, in order to improve surveillance and estimate the prevalence of asymptomatic or subclinical COVID-19 cases. A prospective multicenter study was conducted between March and June 2021 in Greece. Children admitted to the hospital or examined in outpatient clinics for reasons other than COVID-19 and their parents were tested for anti-Spike SARS-CoV-2 IgG in serum. A questionnaire about clinical and demographic data was completed. The study included 823 participants: 427 children and 396 corresponding parents. The overall seroprevalence was 16.4% in parents and 13.8% in children. Among families with ≥ 1 seropositive child or parent, the combination of a seropositive parent and a corresponding seronegative child was 29.6%, a seronegative parent and a corresponding seropositive child was 24.7%, and a seropositive child with a corresponding seropositive parent was 45.7%. Age, level of education, and school or work attendance were not significantly associated with increased seropositivity. On the contrary, ethnic minority of Roma, close contact with known COVID-19 case, previous symptoms consistent with COVID-19, and mass gatherings were risk factors for seropositivity. CONCLUSION: The spread of SARS-CoV-2 during a period of lockdown in Greece was low in children and comparable to adults most likely due to intrafamilial transmission. Accordingly, it is unlikely that children have boosted virus transmission. WHAT IS KNOWN: • In the earliest months of the pandemic, it was demonstrated that children had significantly lower seroprevalence rates than the older age groups, due to the fact that children had decreased exposure to the virus, because of early public health interventions, such as school and day care closure. • Later, further studies reported that children have similar incidence rate of SARS-CoV-2 infection compared to adults in households and community settings. WHAT IS NEW: • In this seroprevalence study, the spread of SARS-CoV-2 infection during a period of lockdown in Greece with the predominance of the Alpha-variant was particularly low in children and comparable to adults, most likely due to intrafamilial transmission. • These study findings will be useful for decisions regarding non-pharmaceutical interventions during the pandemic, and especially, to guide in designing and implementing appropriate containment measures for schools and social gatherings.

Vaccination coverage rates and attitudes towards mandatory vaccinations among healthcare personnel in tertiary-care hospitals in Greece.

OBJECTIVES: Our aim was to estimate vaccination and susceptibility rates against vaccine-preventable diseases among healthcare personnel (HCP) in eight hospitals. METHODS: Cross-sectional survey. RESULTS: A total of 1284 HCP participated (physicians: 31.3%, nursing personnel: 36.6%, paramedical personnel: 11.1%, administrative personnel: 13.2%, supportive personnel: 7.3%). Vaccination rates were 32.9% against measles and mumps, 38.1% against rubella, 5.7% against varicella, 9.2% against hepatitis A, 65.8% against hepatitis B, 31.8% against tetanus-diphtheria, 7.1% against pertussis, 60.2% against influenza, and 80.1% against COVID-19. Susceptibility rates were as follows: 27.8% for measles, 39.6% for mumps, 33.4% for rubella, 22.2% for varicella, 86.3% for hepatitis A, 34.2% for hepatitis B, 68.2% for tetanus-diphtheria, and 92.9% for pertussis. Older HCP had higher susceptibility rates against mumps, rubella, varicella, hepatitis A, hepatitis B, tetanus-diphtheria, and pertussis (p-values <0.001 for all). Mandatory vaccinations were supported by 81.85% of HCP. CONCLUSIONS: Although most HCPs supported mandatory vaccinations, significant vaccination gaps, and susceptibility rates were recorded. The proportion of susceptible HCP to measles, mumps, rubella, and varicella has increased in the past decade, mostly because of reduction in acquired cases of natural illness. Vaccination programs for HCP should be developed. A national registry to follow HCP's vaccination rates is urgently needed.

SARS-CoV-2 molecular testing in Greek hospital paediatric departments: a nationwide study.

As most children infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) present with mild symptoms or they are asymptomatic, the optimal strategy for molecular testing it is not well defined. The aim of the study was to determine the extent and aetiology of molecular testing for SARS-CoV-2 in Greek paediatric departments during the first phase of the pandemic and identify possible differences in incidence, depending on the age group and geographical area. We conducted a nationwide study of molecular testing for SARS-CoV-2 of children in paediatric departments between March and June 2020. A total of 65 paediatric departments participated in the study, representing 4901 children who were tested for SARS-CoV-2 and 90 (1.8%) were positive. Most paediatric cases were associated with topical outbreaks. Adolescents 11-16 years had the highest positivity rate (3.6%) followed by children 6-10 years (1.9%). However, since the testing rate significantly differed between age groups, the modified incidence of SARS-CoV-2 infection per age group was highest in infants <1 year (19.25/105 population). Most children tested presented with fever (70.9%), respiratory (50.1%) or gastrointestinal symptoms (28.1%). Significant differences were detected between public and private hospitals regarding the positivity rate (2.34% vs. 0.39%, P-value <0.001). Significant variation in SARS-CoV-2 molecular testing positivity rate and incidence between age groups indicate discrepancies in risk factors among different age groups that shall be considered when ordering molecular testing.

Children and Adolescents With SARS-CoV-2 Infection: Epidemiology, Clinical Course and Viral Loads.

BACKGROUND: There is limited information on severe acute respiratory syndrome virus 2 (SARS-CoV-2) infection in children. METHODS: We retrieved data from the national database on SARS-CoV-2 infections. We studied in-family transmission. The level of viral load was categorized as high, moderate, or low based on the cycle threshold values. RESULTS: We studied 203 SARS-CoV-2-infected children (median age: 11 years; range: 6 days to 18.4 years); 111 (54.7%) had an asymptomatic infection. Among the 92 children (45.3%) with coronavirus disease 2019 (COVID-19), 24 (26.1%) were hospitalized. Infants <1 year were more likely to develop COVID-19 (19.5% of all COVID-19 cases) (P-value = 0.001). There was no significant difference between viral load and age, sex, underlying condition, fever and hospitalization, as well as between type of SARS-CoV-2 infection and age, sex, underlying condition and viral load. Transmission from a household member accounted for 132 of 178 (74.2%) children for whom the source of infection was identified. An adult member with COVID-19 was the first case in 125 (66.8%) family clusters. Child-to-adult transmission was found in one occasion only. CONCLUSIONS: SARS-CoV-2 infection is mainly asymptomatic or mild during childhood. Adults appear to play a key role in spread of the virus in families. Most children have moderate or high viral loads regardless of age, symptoms or severity of infection. Further studies are needed to elucidate the role of children in the ongoing pandemic and particularly in light of schools reopening and the need to prioritize groups for vaccination, when COVID-19 vaccines will be available.